(NOTE: You only have 60 seconds to pair the Bluetooth scanner from the time you connect it to the car — to the time of entering the Pairing code. If more then 60 second pass — then Pairing code will be rejected and you'll have to plug out the scanner and try again. So have your Bluetooth devices window open, so you can immediately connect as soon as you see ELM327/OBDII/Unknown Device show up.)

In the upper right of the Apple menu bar click the Bluetooth symbol. Scroll down to set up Bluetooth device (You may need to turn Bluetooth "On" first).

In case the Bluetooth icon is not present in the menu bar, to go System Preferences » Bluetooth » and check the "Show Bluetooth status in the menu bar" box.

The Bluetooth setup assistant will search for devices automatically. The Bluetooth name for the ELM327 interfaces will be either "OBDII" or "CBT". Or even different.

If your device does not appear, ensure the ignition is "on" and your Bluetooth OBD 2 interface is securely connected. Verify that the OBD 2 interface is powered which is indicated by a steady red LED on the device.